The general techniques of automatic milking are widely known.
It is convenient that an animal to be milked by an automatic procedure is restrained to some degree as, unless the animal is very docile, it is likely to move so much that the milking procedure is interrupted. On the other hand too much or too severe restraint is very likely to upset the animal causing excessive movement and possibly affecting milk yields. For automatic milking it is important that the animal is not deterred from entering a milking stall. In automatic milking procedures animals are free to present themselves for milking at any time. If the animal has not been milked recently it will be admitted to a stall, prepared for milking and have the teat cluster attached, all by machinery without human intervention. The quick and reliable attachment of the teat cluster is an important phase and if the animal is restless attachment is made more difficult as the teats move and the teat cluster can not always "track" the teats rapidly enough.
The design of the stall has been found to have considerable effect on the readiness of animals to present themselves for an automatic milking procedure and on the behaviour of the animal during milking by such a procedure. The stall design can thus have a significant adverse effect on the benefit expected from automatic milking procedures if the design makes the animals feel uncomfortable.
One approach for stall design for automatic milking is to closely constrain the animal by making the stall a close fit to the animal. This will reduce teat movement resulting from movement of the animal as a whole but the close fit of the stall makes the animal restless and movement of individual legs, which is still possible, can cause significant teat movement. If the leg movements become kicks the milking equipment may be damaged or the animal injured.
Another approach is to constrain the rear feet so that the rear legs are relatively still and, as a result, the teats should not move much. However the constraints, such as cross-wise slopes or barriers to urge the feet apart or claws to restrain the feet, are not very attractive from the animal welfare aspect and are not very effective unless extremely restrictive, with the above disadvantages resulting from restless animals.
EP-A1-0191517 shows an arrangement in which a portion of stall floor beneath an animal in the stall can be pivoted rearwardly up against the front of the rear legs to control the position of the legs and a further portion of floor, on which the rear legs are placed, slideable rearwardly to move the rear legs rearwardly. Separately or in combination these moving parts force the animal to adopt a position in which the rear of the animal is held against a position determining buffer and in which the rear legs are moved to the rear to improve the access to the udder. Another rearwardly pivotable plate can act similarly to the first one but against the front legs.
Such an arrangement exerts considerable restraint on the animal and this, with the movement of the floor while the animal is on it, is unlikely, in accordance with present understanding, to encourage the animal to readily enter the stall or remain in a quiet state for milking.
FR-A-2605841 discloses a mobile animal stall for a rotating milking parlour. The animal enters the stall for milking, the stall is then moved in a circular path while milking takes place. The particular feature of the stall is a floor, the front part of which moves once the animal is in place in the stall. On entering the stall the animal is encouraged by the placing of a food trough to place its neck in a latch which prevents the animal from leaving the stall. The front part of the floor, on which the front legs of the animal stand, is then raised. This compels the animal to move its back legs apart and, so as not to fall because of the transfer of the weight of the animal to rear, not to raise the back legs. Secured in this position the attachment of teat cups is facilitated by the moved-apart back legs.
Again such an arrangement is considered unlikely to encourage the animal to enter the stall or remain quiet for milking both because of the considerable restraint and the movement of the floor when the animal is standing on it.
Furthermore both such arrangements require complicated mechanisms which are bulky and not appropriate to the arduous conditions of a milking parlour.